The long term objective of this research is to understand the fine controls of ovarian function and thus to provide opportunities to control fertility and alleviate some forms infertility in women. The present dimension is to understand the paracrine control of follicular development and ovulation through the study of the local production and some of the biological actions in common between prostaglandins (PGs) and relaxin in the follicle of the pig and rat. The distribution of their sites of production and their receptors in situ in pig and rat follicles will be determined throughout follicular development and after inhibition of ovulation. The factors modulating this local production of PGE2, PGF2Alpha and relaxin by isolated granulosa and theca cells as well as follicle wall will be studied in vitro. The endogenous release of paracrine relaxin into porcine follicular fluid will be deduced from measurements by RIA and compared with PGE2 and PGF2Alpha levels during follicular development. Selected biological actions in common between PGE2, PGF2Alpha and relaxin, the release of enzymes involved in collagen remodelling, will be related to the localization of their respective receptors in the follicle during development. Methodology will include the determination of the sites of hormone production in situ by immunocytochemistry and hormone receptor localization by quantitative light microscopic autoradiography. Hormone concentrations in follicular fluids and in media from in vitro cultures of follicular tissue will be measured by conventional radioimmunoassay. The biological actions of the prostaglandins and relaxin in common will be determined by measuring the release of plasminogen activator and collagenase by isolated cells in vitro.